1. Field of the Invention
This invention relates generally to metal plate gaskets for use in heavy duty diesel engine applications, and more particularly to the sealing of the combustion chambers of such engines.
2. Related Art
Metal plate gaskets of conventional construction for use in sealing a cylinder head to a block of a heavy duty diesel engine include a solid metal plate formed with a plurality of openings corresponding to various fluid passages communicating between the head and block. At least one of the openings is a combustion opening which surrounds a piston cylinder of the block. A fire ring of copper or the like is set in the plate opening and is crushed to the thickness of the plate as the head is bolted to the block. The fire ring serves to seal the combustion opening against leakage. The plate serves to limit the plastic deformation of the fire ring. One drawback to such fire rings is that they do not recover their shape of the load is removed or decreased. During operation of the engine, the load applied between the head and block varies depending upon the stroke cycle and operating temperature, presenting an opportunity for the head or block to draw away from the fire ring and thus decreasing the sealing effectiveness of such rings.
Other metal plate gasket constructions utilize a conventional, plastically deformable fire ring wrapped in a metal armoring of steel. The steel armor thus relies on the strength and plastic deformation properties of the fire crush ring core to achieve sealing, and thus shares the same deficiencies as the fire ring described previously.